Well, this situation would appear to have sorted itself out lol
Hendrix has come home just that little bit better able to stand up to Jagger. He had been bit of a lap cat since he came home which I was really enjoying, but I noticed he was starting to look at the cat tree with jagger snoozing away in it. Yesterday, whilst jagger was elsewhere he helped himself. When jagger noticed, he jumped up on the tree, sniffed at Hendrix in the top bed and slapped him with his paw. Hendrix didn't even blink an eye and totally ignored him.
Hopefully, they will soon be able to sleep on it together. Last night jagger went and slept in hendrix's snuggle bed instead.
But there was no actual aggro over Hendrix using the tree and previously jagger would chase him off it.
They actually are more bonded than ever, I really didn't think things would go so well with Hendrix not being here for two and a half weeks. But Hendrix took matters into his own hands (sorry, paws) and within a couple of days being home was lying in wait for jagger, pouncing on him and they would then chase each other all over the house and having a fine old time!